From the command line,
R CMD INSTALL plyr_x.y.z.tar.gz
If you don't have permission to write to the standard library directory and can't use sudo
to override, you can install it somewhere else via
R CMD INSTALL -l <user_lib> plyr_x.y.z.tar.gz
where <user_lib>
is a directory you can write to. You may need to specify lib.loc
when subsequently loading the package, if <user_lib>
is not in .libPaths
(see @DWin's answer).
See http://cran.r-project.org/doc/manuals/R-admin.html for more information; R CMD INSTALL --help
may also be useful, albeit terse.